Perform Unmount/Mount/ResizeFS

Sneaky is now able to handle messages for unmounting volume device,
mounting volume device, and resizing the filesystem as is required
by Trove refactoring to get Cinder Volume resizes working.

Also this adds free and total to Filesystsem stats.
Merge pull request #10 from jcru/unmount_volume_final

Perform Unmount/Mount/ResizeFS